Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
int a[4]={1,0,-1,0};
int b[4]={0,1,0,-1};
struct p
{
    int x,y,time;
};
char c[55][55];
int v[55][55],d[55][55];
int main()
{
    int h,w;
    queue<p>q;
    scanf("%d%d",&h,&w);
    int sum=h*w;
    for(int i=1;i<=h;i++)
    {
        for(int j=1;j<=w;j++)
        {
            cin>>c[i][j];
            if(c[i][j]=='#')sum--;
        }
    }
    q.push({1,1,1});
    while(!q.empty())
    {
        p k=q.front();
        q.pop();
        if(v[k.x][k.y])continue;
        v[k.x][k.y]=1;
        d[k.x][k.y]=k.time;
        for(int i=0;i<4;i++)
        {
            if(c[k.x+a[i]][k.y+b[i]]=='.')
            {
                q.push({k.x+a[i],k.y+b[i],k.time+1});
            }
        }
    }
    if(d[h][w])printf("%d\n",sum-d[h][w]);
    else printf("-1\n");
}